Liu Xin-Jun, Wang Shu-Juan, Liu Cheng, Fan Li-Ru, Fu Cui-Qing, Qi Kun, Su Wen-Kang
Hebei Province Ecology Environmental Monitoring Center, Shijiazhuang 050037, China.
Hebei Provincial Academy of Ecological Environmental Science, Shijiazhuang 050037, China.
Huan Jing Ke Xue. 2022 Mar 8;43(3):1268-1276. doi: 10.13227/j.hjkx.202106253.
Many restrictive measures were implemented in China from January-February 2020 to control the rapid spread of COVID-19. Many studies reported that the COVID-19 lockdown impacted PM, SO, volatile organic compounds (VOCs), etc. VOCs play important roles in the production of ozone and PM. Ambient VOCs in Xiong'an were measured from December 25, 2019 to January 24, 2020 (prior to epidemic prevention, P1) and from January 25, 2020 to February 24, 2020 (during epidemic prevention, P2) through a VOCs online instrument. In the study, VOCs characteristics and ozone generation potential (OFP) of ambient VOCs were analyzed, and source apportionment of VOCs were analyzed by using Positive Matrix Factorization (PMF). The results showed that (TVOCs) during epidemic prevention and control was 45.1×10, which was approximately half of that before epidemic prevention and control (90.5×10). The chemical composition of VOCs showed significant changes after epidemic prevention and control, the contribution rate of alkanes increased from 37.6% to 53.8%, and the contribution rate of aromatic hydrocarbons and halogenated hydrocarbons decreased from 13.3% and 12.0% to 7.5% and 7.8%, respectively. Aromatic hydrocarbons, halogenated hydrocarbons, and OVOCs decreased by more than 60%. Seven types of the top ten species were the same before and during the epidemic prevention and control, mainly low-carbon alkanes, olefins, aldehydes, and ketones. Dichloromethane, trichloromethane, and BTEXs decreased significantly. The OPP was 566 μg·m and 231 μg·m in P1 and P2, respectively. The OPP of VOCs decreased by more than 30%. The proportion of OFP contribution of aromatic hydrocarbons decreased significantly after the epidemic prevention and control, and the proportion of OFP contribution of alkanes and alkynes increased significantly. Positive matrix factorization (PMF) was then applied for VOCs sources apportionment. Six sources were identified, including background sources, oil-gas volatile sources, combustion sources, industrial sources, solvent use sources, and vehicle exhaust sources. The results showed that after the epidemic prevention and control, the contribution rate of solvent use sources to TVOCs decreased from 24% to 9%. The contribution rates of background sources, oil-gas volatile sources, and combustion sources increased from 13%, 34%, and 24% to 6%, 14%, and 13%, respectively. The relative contributions of vehicle exhaust sources before and after epidemic prevention and control were 21% and 18%, respectively. The observation points were affected by the emission of VOCs from paroxysmal industrial sources before the epidemic prevention and control. The emission was stopped after the epidemic prevention and control, and its contribution rate was reduced from 22% before the epidemic prevention and control to 1%. The concentrations of industrial sources, solvent sources, motor vehicle tail gas sources, and combustion sources decreased by 97%, 82%, 61%, and 15%, respectively, after the epidemic prevention and control. The concentration of background sources remained stable, and the concentration of oil and gas volatile sources increased by 7%. The control of production and traffic activities cannot reduce the emission of VOCs from oil and gas volatile sources, which is the focus of VOCs control in Xiong'an.
2020年1月至2月期间，中国实施了许多限制措施以控制新冠病毒肺炎（COVID-19）的快速传播。许多研究报告称，COVID-19封锁措施对颗粒物（PM）、二氧化硫（SO）、挥发性有机化合物（VOCs）等产生了影响。VOCs在臭氧和PM的生成中起着重要作用。通过VOCs在线仪器，于2019年12月25日至2020年1月24日（疫情防控前，P1）以及2020年1月25日至2月24日（疫情防控期间，P2）对雄安地区的环境VOCs进行了测量。在该研究中，分析了环境VOCs的特征和臭氧生成潜力（OFP），并采用正定矩阵因子分解法（PMF）对VOCs进行了源解析。结果表明，疫情防控期间的总挥发性有机化合物（TVOCs）为45.1×10，约为疫情防控前（90.5×10）的一半。疫情防控后，VOCs的化学组成发生了显著变化，烷烃的贡献率从37.6%增至53.8%，芳烃和卤代烃的贡献率分别从13.3%和12.0%降至7.5%和7.8%。芳烃、卤代烃和含氧挥发性有机物（OVOCs）减少了60%以上。疫情防控前后十大物种中的七种相同，主要是低碳烷烃、烯烃、醛类和酮类。二氯甲烷、三氯甲烷和苯系物显著减少。P1和P2阶段的臭氧生成潜势（OFP）分别为566 μg·m和231 μg·m。VOCs的OFP下降了30%以上。疫情防控后，芳烃的OFP贡献率显著下降，烷烃和炔烃的OFP贡献率显著增加。然后应用正定矩阵因子分解法（PMF）对VOCs进行源解析。识别出六种源，包括背景源、油气挥发源、燃烧源、工业源、溶剂使用源和机动车尾气源。结果表明，疫情防控后，溶剂使用源对TVOCs的贡献率从24%降至9%。背景源、油气挥发源和燃烧源的贡献率分别从13%、34%和24%增至6%、14%和13%。疫情防控前后机动车尾气源的相对贡献率分别为21%和18%。疫情防控前观测点受阵发性工业源VOCs排放影响，疫情防控后该排放停止，其贡献率从疫情防控前的22%降至1%。疫情防控后，工业源、溶剂源、机动车尾气源和燃烧源的浓度分别下降了97%、82%、61%和15%。背景源浓度保持稳定，油气挥发源浓度增加了7%。生产和交通活动的管控无法降低油气挥发源的VOCs排放，这是雄安地区VOCs控制的重点。
